No matter how the crisis in Egypt turns out, it’s not likely to be positive. Either the regime will survive or it won’t. If it does, the people of Egypt will most likely live under even more repressive control. If the regime doesn’t survive, the question is who and what will succeed it. The Islamist Muslim Brotherhood could end up in power, either openly or behind the scenes, in the absence of any other organized opposition. That has serious negative implications for the region and for U.S. interests. And the Egyptian people would likely live under even worse conditions than now — think not so much about the Taliban as about Iran since the fall of the Shah.

According to David Clark, an MIT computer scientist whose research focuses on Internet architecture and development, a government’s ability to control the Internet depends on its control of Internet Service Providers (ISPs), the private sector companies that grant Internet access to customers.

“ISPs have direct control of the Internet, so what happens in any country depends on the control that the state has over those ISPs,” Clark told Life’s Little Mysteries in an e-mail. “Some countries regulate the ISPs much more heavily. China has in the past ‘turned off’ the Internet in various regions.”

When a government orders the ISP to disable service, Clark explained, “they have lots of ways of doing it technically. They could power down devices (which is sort of like unplugging things), or change the routing tables (which is more like a “digital kill,” and can serve to allow selective services to stay up).”

In Egypt it was easier because the largest ISP is Telecom Egypt, which the government controls. But there was still “leakage” because one small ISP stayed up for a while, and some people, to include the press, had access via old-style satellite phones, smart phones, and other routes to the internet. Cell phones were also disabled in Egypt, but anyone with a direct route to a satellite also still had at least limited cell phone service.

Turning off the internet is far more difficult, if not impossible, in a large, modern, highly technological country, none of which describes Egypt. In the U.S., the five largest ISPs control about half of all internet traffic. However, there is a huge number of ISPs beyond those five. If the president were to personally call all the ISPs and tell them to turn it off, he would probably get a chorus of raspberries coming back at him down the phone line.

Even if major internet nodes were physically shut down, the system would quickly re-route itself. As the article noted, “The destruction of the major switching center in south Manhattan on 9/11 ‘healed’ in about 15 minutes as the protocols routed around the outage.”

There’s been discussion in the U.S. about whether the president should have the power to shut down the internet in case of an emergency, such as a nationwide cyber attack. A bill, “The Protecting Cyberspace as a National Asset Act of 2010,” was introduced in the U.S. Senate last year but wasn’t passed. Despite the uproar it caused in some quarters, it didn’t give the president new powers; in a time of war (whatever that means these days), the president could try to shut down the internet under existing law. The bill would further define and regularize that power over the internet, limiting it to 120 days unless Congress agreed to additional time.

The bill introduced in the Senate during the last session, or something like it, is probably a good idea. If the U.S. in particular or the worldwide internet were to come under attack, it would be useful to have laws and procedures in place to do what’s necessary to protect such things as the financial system, the defense system, sensitive records, etc. However, it seems unlikely that such a law can be passed, given opposition from both the left and right, each with their own set of conspiracy theories and visceral fears.

The whole discussion may be academic in any event. The internet may someday be completely shut down by someone with more power than any national leader — a pimply-faced teenager with a computer in his parents’ basement in Des Moines or in a shabby apartment block in Novosibirsk.